| 摘要 |
1,064,238. Engraving diffraction gratings. W. R. HORSFIELD. Feb. 23, 1965 [April 1, 1964], No. 13498/64. Heading B6J. [Also in Divison G1] Apparatus for ruling a diffraction grating comprises a blank supporting carriage 2 which is movable between each ruling operation by means of an hydraulic ram 18 operated by a positive displacement pump 58, the effective volume delivered by the pump and its stroke being controlled by a servomotor 102 actuated by an interferometer which measures the position of the carriage 2 at succeeding ruling positions. The carriage 2 slides on guides 4, 90 to 95% of its weight being taken by immersing the lower part thereof in mercury. Fixed guides 10 support a cross-carriage 12 carrying a diamond ruling tool. A motor 40 drives a power shaft 48 through a belt drive 46 and this shaft is used to control various operations of the apparatus either directly or by use of microswitches. The positive displacement pump 58 is actuated by an eccentric in the shaft 48 acting on a compound lever arrangement 54. The pump output is applied to the hydraulic ram 18 by way of a slide valve 60 also operated by the shaft 48. The ram 28 acts on the carriage 2 by way of a connecting rod 24 held in place by wires 25 tensioned using a pulley and weight arrangement 26. The position of the carriage 2 is measured using the interferometer in which comprises a light source 28, a beam splitter 30, a fixed mirror 32, a mirror 34 attached to the carriage 2 and a photomultiplier 38. The output of the photomultiplier is fed to an amplifier 94 which actuates the servomotor 102 to adjust the effective volume of the fluid delivered by the pump 58 and the stroke of the pump. This adjustment is described in the Specification and takes place through an electromagnetic clutch controlled by a microswitch actuated by the shaft 48. The amplifier output may be monitored using an oscilloscope 98 or meter 99. A rotatable optical plate 139 is included in the path of the light to the fixed mirror 32 to compensate for changes in atmospheric pressure. The plate 139 is rotated under the control of an adjustable mercury barometer described in the Specification. A second amplifier 116 is also provided to compensate for the changes in path length to the mirror 34 as the carriage 2 moves. The cross-carriage 12 is reciprocated by a drive from the shaft 48, means being provided for raising the ruling tool clear of the blank during the return motion after ruling. The crosscarriage 12 may carry two ruling tools if desired. |
